As carrier Jason Herald walked toward a house on Chain Bridge Road in Fairfax City on Tuesday afternoon, he said, "I could hear a sort of slushing sound." When he neared the front door, something made him look up. At that moment, the large two-story brick colonial decided to shed the snow blanket from its roof.

Herald, 34, is pretty nimble-footed, and he'd warmed up for this by walking his 6 1/2 -mile route for several hours. "I saw it coming at the last second and backed out of the way," he said calmly, and the heavy white mass plopped harmlessly at his feet.

Postal carriers continued their daily slog Tuesday through the deepening slush and mountainous piles of dirty snow, keeping one eye on the darkening sky and handling some problems rarely encountered in the Washington area. Standalone mailboxes are sometimes completely covered. Roadside boxes, normally filled by a carrier leaning out of a vehicle, must be visited on foot.

But the U.S. Postal Service was determined to keep the mail coming, regardless of rain or sleet or repeated blizzards. A spokeswoman said 80 percent of the mail was delivered Monday.

In Fairfax City, one supervisor slept in the post office Friday night to ensure he'd be there Saturday, as Blizzard I was descending. "I gathered up some groceries and some extra clothes" and slept on a mail cart, Christian Ropple said. But only about a dozen of the 43 carriers assigned to Fairfax made it in Saturday, and the postal service canceled deliveries for the first time since 1996.

Postal officials said that there is increased urgency for many deliveries now because medications are often sent through the mail. "We really make sure to deliver that quickly," said Jamie Congleton, the Fairfax postmaster.

The rattling packages make up an increasing part of Herald's load. "Medications -- now that puts the pressure on," he said with a smile.

Herald has worked the same route for more than 10 years, a combination of single-family houses in north Fairfax City and businesses along Route 50. People are often glad to see "the mailman," but they were really happy to see Herald trudging through unplowed sidewalks and snow-packed front yards.

"You want some hot chocolate?" offered one woman.

"He's like a member of the family," said Boo Perkins, with two kids orbiting her ankles. "He'll stop and chat. He's a great guy."

Herald had a kind word for everyone, but he was also mindful that the snow was slowing him down. The route typically takes seven hours and 12 minutes -- the Postal Service is very exact about these things -- but Herald knew that Tuesday would be different. Not being able to make many of his deliveries to roadside boxes without getting out of his van was definitely a setback.

And then there was simply going from house to house. There are different strategies for walking through three feet of snow. Herald favors the aggressive attack: quick, high steps with toes pointed down, to better push through the frozen powder. But it's even tougher to maintain balance with a mail satchel around one shoulder and a stack of bills and magazines along one arm.

Still, he favored plowing through snow rather than circling back to the street for each house. "It may be harder on the thighs," said the ex-Marine and father of four, "but the sidewalks get icy and you're more likely to fall. And I've fallen so many times." Herald said he is such an experienced faller now that he no longer makes eye contact with those who watch his mail go flying, followed by his rapid recovery.

Not long after he'd started Tuesday, his official Postal Service jacket came off. "I'm burning off all the Taco Bell I ate last night," he said.

Then the official wool Postal Service hat was removed. "I haven't sweated like this since July," he said. It was 25 degrees. Later, he went with the Postal Service sun hat. An official Postal Service kilt apparently was under consideration by top officials at one time, and Herald said he'd have worn it, but it was never issued.